src/coremods/core_dns.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2013 Adam <Adam@anope.org>
   5  *   Copyright (C) 2003-2013 Anope Team <team@anope.org>
   6  *
   7  * This file is part of InspIRCd.  InspIRCd is free software: you can
   8  * redistribute it and/or modify it under the terms of the GNU General Public
   9  * License as published by the Free Software Foundation, version 2.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  14  * details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "inspircd.h"
  21 #include "modules/dns.h"
  22 #include <iostream>
  23 #include <fstream>
  24
  25 #ifdef _WIN32
  26 #include <Iphlpapi.h>
  27 #pragma comment(lib, "Iphlpapi.lib")
  28 #endif
  29
  30 using namespace DNS;
  31
  32 /** A full packet sent or recieved to/from the nameserver
  33  */
  34 class Packet : public Query
  35 {
  36         static bool IsValidName(const std::string& name)
  37         {
  38                 return (name.find_first_not_of("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-") == std::string::npos);
  39         }
  40
  41         void PackName(unsigned char* output, unsigned short output_size, unsigned short& pos, const std::string& name)
  42         {
  43                 if (pos + name.length() + 2 > output_size)
  44                         throw Exception("Unable to pack name");
  45
  46                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Packing name " + name);
  47
  48                 irc::sepstream sep(name, '.');
  49                 std::string token;
  50
  51                 while (sep.GetToken(token))
  52                 {
  53                         output[pos++] = token.length();
  54                         memcpy(&output[pos], token.data(), token.length());
  55                         pos += token.length();
  56                 }
  57
  58                 output[pos++] = 0;
  59         }
  60
  61         std::string UnpackName(const unsigned char* input, unsigned short input_size, unsigned short& pos)
  62         {
  63                 std::string name;
  64                 unsigned short pos_ptr = pos, lowest_ptr = input_size;
  65                 bool compressed = false;
  66
  67                 if (pos_ptr >= input_size)
  68                         throw Exception("Unable to unpack name - no input");
  69
  70                 while (input[pos_ptr] > 0)
  71                 {
  72                         unsigned short offset = input[pos_ptr];
  73
  74                         if (offset & POINTER)
  75                         {
  76                                 if ((offset & POINTER) != POINTER)
  77                                         throw Exception("Unable to unpack name - bogus compression header");
  78                                 if (pos_ptr + 1 >= input_size)
  79                                         throw Exception("Unable to unpack name - bogus compression header");
  80
  81                                 /* Place pos at the second byte of the first (farthest) compression pointer */
  82                                 if (compressed == false)
  83                                 {
  84                                         ++pos;
  85                                         compressed = true;
  86                                 }
  87
  88                                 pos_ptr = (offset & LABEL) << 8 | input[pos_ptr + 1];
  89
  90                                 /* Pointers can only go back */
  91                                 if (pos_ptr >= lowest_ptr)
  92                                         throw Exception("Unable to unpack name - bogus compression pointer");
  93                                 lowest_ptr = pos_ptr;
  94                         }
  95                         else
  96                         {
  97                                 if (pos_ptr + offset + 1 >= input_size)
  98                                         throw Exception("Unable to unpack name - offset too large");
  99                                 if (!name.empty())
 100                                         name += ".";
 101                                 for (unsigned i = 1; i <= offset; ++i)
 102                                         name += input[pos_ptr + i];
 103
 104                                 pos_ptr += offset + 1;
 105                                 if (compressed == false)
 106                                         /* Move up pos */
 107                                         pos = pos_ptr;
 108                         }
 109                 }
 110
 111                 /* +1 pos either to one byte after the compression pointer or one byte after the ending \0 */
 112                 ++pos;
 113
 114                 if (name.empty())
 115                         throw Exception("Unable to unpack name - no name");
 116
 117                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Unpack name " + name);
 118
 119                 return name;
 120         }
 121
 122         Question UnpackQuestion(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 123         {
 124                 Question q;
 125
 126                 q.name = this->UnpackName(input, input_size, pos);
 127
 128                 if (pos + 4 > input_size)
 129                         throw Exception("Unable to unpack question");
 130
 131                 q.type = static_cast<QueryType>(input[pos] << 8 | input[pos + 1]);
 132                 pos += 2;
 133
 134                 // Skip over query class code
 135                 pos += 2;
 136
 137                 return q;
 138         }
 139
 140         ResourceRecord UnpackResourceRecord(const unsigned char* input, unsigned short input_size, unsigned short& pos)
 141         {
 142                 ResourceRecord record = static_cast<ResourceRecord>(this->UnpackQuestion(input, input_size, pos));
 143
 144                 if (pos + 6 > input_size)
 145                         throw Exception("Unable to unpack resource record");
 146
 147                 record.ttl = (input[pos] << 24) | (input[pos + 1] << 16) | (input[pos + 2] << 8) | input[pos + 3];
 148                 pos += 4;
 149
 150                 //record.rdlength = input[pos] << 8 | input[pos + 1];
 151                 pos += 2;
 152
 153                 switch (record.type)
 154                 {
 155                         case QUERY_A:
 156                         {
 157                                 if (pos + 4 > input_size)
 158                                         throw Exception("Unable to unpack resource record");
 159
 160                                 irc::sockets::sockaddrs addrs;
 161                                 memset(&addrs, 0, sizeof(addrs));
 162
 163                                 addrs.in4.sin_family = AF_INET;
 164                                 addrs.in4.sin_addr.s_addr = input[pos] | (input[pos + 1] << 8) | (input[pos + 2] << 16)  | (input[pos + 3] << 24);
 165                                 pos += 4;
 166
 167                                 record.rdata = addrs.addr();
 168                                 break;
 169                         }
 170                         case QUERY_AAAA:
 171                         {
 172                                 if (pos + 16 > input_size)
 173                                         throw Exception("Unable to unpack resource record");
 174
 175                                 irc::sockets::sockaddrs addrs;
 176                                 memset(&addrs, 0, sizeof(addrs));
 177
 178                                 addrs.in6.sin6_family = AF_INET6;
 179                                 for (int j = 0; j < 16; ++j)
 180                                         addrs.in6.sin6_addr.s6_addr[j] = input[pos + j];
 181                                 pos += 16;
 182
 183                                 record.rdata = addrs.addr();
 184
 185                                 break;
 186                         }
 187                         case QUERY_CNAME:
 188                         case QUERY_PTR:
 189                         {
 190                                 record.rdata = this->UnpackName(input, input_size, pos);
 191                                 if (!IsValidName(record.rdata))
 192                                         throw Exception("Invalid name"); // XXX: Causes the request to time out
 193
 194                                 break;
 195                         }
 196                         default:
 197                                 break;
 198                 }
 199
 200                 if (!record.name.empty() && !record.rdata.empty())
 201                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, record.name + " -> " + record.rdata);
 202
 203                 return record;
 204         }
 205
 206  public:
 207         static const int POINTER = 0xC0;
 208         static const int LABEL = 0x3F;
 209         static const int HEADER_LENGTH = 12;
 210
 211         /* ID for this packet */
 212         RequestId id;
 213         /* Flags on the packet */
 214         unsigned short flags;
 215
 216         Packet() : id(0), flags(0)
 217         {
 218         }
 219
 220         void Fill(const unsigned char* input, const unsigned short len)
 221         {
 222                 if (len < HEADER_LENGTH)
 223                         throw Exception("Unable to fill packet");
 224
 225                 unsigned short packet_pos = 0;
 226
 227                 this->id = (input[packet_pos] << 8) | input[packet_pos + 1];
 228                 packet_pos += 2;
 229
 230                 this->flags = (input[packet_pos] << 8) | input[packet_pos + 1];
 231                 packet_pos += 2;
 232
 233                 unsigned short qdcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 234                 packet_pos += 2;
 235
 236                 unsigned short ancount = (input[packet_pos] << 8) | input[packet_pos + 1];
 237                 packet_pos += 2;
 238
 239                 unsigned short nscount = (input[packet_pos] << 8) | input[packet_pos + 1];
 240                 packet_pos += 2;
 241
 242                 unsigned short arcount = (input[packet_pos] << 8) | input[packet_pos + 1];
 243                 packet_pos += 2;
 244
 245                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "qdcount: " + ConvToStr(qdcount) + " ancount: " + ConvToStr(ancount) + " nscount: " + ConvToStr(nscount) + " arcount: " + ConvToStr(arcount));
 246
 247                 if (qdcount != 1)
 248                         throw Exception("Question count != 1 in incoming packet");
 249
 250                 this->question = this->UnpackQuestion(input, len, packet_pos);
 251
 252                 for (unsigned i = 0; i < ancount; ++i)
 253                         this->answers.push_back(this->UnpackResourceRecord(input, len, packet_pos));
 254         }
 255
 256         unsigned short Pack(unsigned char* output, unsigned short output_size)
 257         {
 258                 if (output_size < HEADER_LENGTH)
 259                         throw Exception("Unable to pack packet");
 260
 261                 unsigned short pos = 0;
 262
 263                 output[pos++] = this->id >> 8;
 264                 output[pos++] = this->id & 0xFF;
 265                 output[pos++] = this->flags >> 8;
 266                 output[pos++] = this->flags & 0xFF;
 267                 output[pos++] = 0; // Question count, high byte
 268                 output[pos++] = 1; // Question count, low byte
 269                 output[pos++] = 0; // Answer count, high byte
 270                 output[pos++] = 0; // Answer count, low byte
 271                 output[pos++] = 0;
 272                 output[pos++] = 0;
 273                 output[pos++] = 0;
 274                 output[pos++] = 0;
 275
 276                 {
 277                         Question& q = this->question;
 278
 279                         if (q.type == QUERY_PTR)
 280                         {
 281                                 irc::sockets::sockaddrs ip;
 282                                 irc::sockets::aptosa(q.name, 0, ip);
 283
 284                                 if (q.name.find(':') != std::string::npos)
 285                                 {
 286                                         static const char* const hex = "0123456789abcdef";
 287                                         char reverse_ip[128];
 288                                         unsigned reverse_ip_count = 0;
 289                                         for (int j = 15; j >= 0; --j)
 290                                         {
 291                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] & 0xF];
 292                                                 reverse_ip[reverse_ip_count++] = '.';
 293                                                 reverse_ip[reverse_ip_count++] = hex[ip.in6.sin6_addr.s6_addr[j] >> 4];
 294                                                 reverse_ip[reverse_ip_count++] = '.';
 295                                         }
 296                                         reverse_ip[reverse_ip_count++] = 0;
 297
 298                                         q.name = reverse_ip;
 299                                         q.name += "ip6.arpa";
 300                                 }
 301                                 else
 302                                 {
 303                                         unsigned long forward = ip.in4.sin_addr.s_addr;
 304                                         ip.in4.sin_addr.s_addr = forward << 24 | (forward & 0xFF00) << 8 | (forward & 0xFF0000) >> 8 | forward >> 24;
 305
 306                                         q.name = ip.addr() + ".in-addr.arpa";
 307                                 }
 308                         }
 309
 310                         this->PackName(output, output_size, pos, q.name);
 311
 312                         if (pos + 4 >= output_size)
 313                                 throw Exception("Unable to pack packet");
 314
 315                         short s = htons(q.type);
 316                         memcpy(&output[pos], &s, 2);
 317                         pos += 2;
 318
 319                         // Query class, always IN
 320                         output[pos++] = 0;
 321                         output[pos++] = 1;
 322                 }
 323
 324                 return pos;
 325         }
 326 };
 327
 328 class MyManager : public Manager, public Timer, public EventHandler
 329 {
 330         typedef TR1NS::unordered_map<Question, Query, Question::hash> cache_map;
 331         cache_map cache;
 332
 333         irc::sockets::sockaddrs myserver;
 334
 335         static bool IsExpired(const Query& record, time_t now = ServerInstance->Time())
 336         {
 337                 const ResourceRecord& req = record.answers[0];
 338                 return (req.created + static_cast<time_t>(req.ttl) < now);
 339         }
 340
 341         /** Check the DNS cache to see if request can be handled by a cached result
 342          * @return true if a cached result was found.
 343          */
 344         bool CheckCache(DNS::Request* req, const DNS::Question& question)
 345         {
 346                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "cache: Checking cache for " + question.name);
 347
 348                 cache_map::iterator it = this->cache.find(question);
 349                 if (it == this->cache.end())
 350                         return false;
 351
 352                 Query& record = it->second;
 353                 if (IsExpired(record))
 354                 {
 355                         this->cache.erase(it);
 356                         return false;
 357                 }
 358
 359                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: Using cached result for " + question.name);
 360                 record.cached = true;
 361                 req->OnLookupComplete(&record);
 362                 return true;
 363         }
 364
 365         /** Add a record to the dns cache
 366          * @param r The record
 367          */
 368         void AddCache(Query& r)
 369         {
 370                 const ResourceRecord& rr = r.answers[0];
 371                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: added cache for " + rr.name + " -> " + rr.rdata + " ttl: " + ConvToStr(rr.ttl));
 372                 this->cache[r.question] = r;
 373         }
 374
 375  public:
 376         DNS::Request* requests[MAX_REQUEST_ID+1];
 377
 378         MyManager(Module* c) : Manager(c), Timer(3600, true)
 379         {
 380                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 381                         requests[i] = NULL;
 382                 ServerInstance->Timers.AddTimer(this);
 383         }
 384
 385         ~MyManager()
 386         {
 387                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 388                 {
 389                         DNS::Request* request = requests[i];
 390                         if (!request)
 391                                 continue;
 392
 393                         Query rr(*request);
 394                         rr.error = ERROR_UNKNOWN;
 395                         request->OnError(&rr);
 396
 397                         delete request;
 398                 }
 399         }
 400
 401         void Process(DNS::Request* req)
 402         {
 403                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Processing request to lookup " + req->name + " of type " + ConvToStr(req->type) + " to " + this->myserver.addr());
 404
 405                 /* Create an id */
 406                 unsigned int tries = 0;
 407                 int id;
 408                 do
 409                 {
 410                         id = ServerInstance->GenRandomInt(DNS::MAX_REQUEST_ID+1);
 411
 412                         if (++tries == DNS::MAX_REQUEST_ID*5)
 413                         {
 414                                 // If we couldn't find an empty slot this many times, do a sequential scan as a last
 415                                 // resort. If an empty slot is found that way, go on, otherwise throw an exception
 416                                 id = -1;
 417                                 for (unsigned int i = 0; i <= DNS::MAX_REQUEST_ID; i++)
 418                                 {
 419                                         if (!this->requests[i])
 420                                         {
 421                                                 id = i;
 422                                                 break;
 423                                         }
 424                                 }
 425
 426                                 if (id == -1)
 427                                         throw Exception("DNS: All ids are in use");
 428
 429                                 break;
 430                         }
 431                 }
 432                 while (this->requests[id]);
 433
 434                 req->id = id;
 435                 this->requests[req->id] = req;
 436
 437                 Packet p;
 438                 p.flags = QUERYFLAGS_RD;
 439                 p.id = req->id;
 440                 p.question = *req;
 441
 442                 unsigned char buffer[524];
 443                 unsigned short len = p.Pack(buffer, sizeof(buffer));
 444
 445                 /* Note that calling Pack() above can actually change the contents of p.question.name, if the query is a PTR,
 446                  * to contain the value that would be in the DNS cache, which is why this is here.
 447                  */
 448                 if (req->use_cache && this->CheckCache(req, p.question))
 449                 {
 450                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Using cached result");
 451                         delete req;
 452                         return;
 453                 }
 454
 455                 // Update name in the original request so question checking works for PTR queries
 456                 req->name = p.question.name;
 457
 458                 if (SocketEngine::SendTo(this, buffer, len, 0, &this->myserver.sa, this->myserver.sa_size()) != len)
 459                         throw Exception("DNS: Unable to send query");
 460         }
 461
 462         void RemoveRequest(DNS::Request* req)
 463         {
 464                 this->requests[req->id] = NULL;
 465         }
 466
 467         std::string GetErrorStr(Error e)
 468         {
 469                 switch (e)
 470                 {
 471                         case ERROR_UNLOADED:
 472                                 return "Module is unloading";
 473                         case ERROR_TIMEDOUT:
 474                                 return "Request timed out";
 475                         case ERROR_NOT_AN_ANSWER:
 476                         case ERROR_NONSTANDARD_QUERY:
 477                         case ERROR_FORMAT_ERROR:
 478                                 return "Malformed answer";
 479                         case ERROR_SERVER_FAILURE:
 480                         case ERROR_NOT_IMPLEMENTED:
 481                         case ERROR_REFUSED:
 482                         case ERROR_INVALIDTYPE:
 483                                 return "Nameserver failure";
 484                         case ERROR_DOMAIN_NOT_FOUND:
 485                         case ERROR_NO_RECORDS:
 486                                 return "Domain not found";
 487                         case ERROR_NONE:
 488                         case ERROR_UNKNOWN:
 489                         default:
 490                                 return "Unknown error";
 491                 }
 492         }
 493
 494         void OnEventHandlerError(int errcode) CXX11_OVERRIDE
 495         {
 496                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "UDP socket got an error event");
 497         }
 498
 499         void OnEventHandlerRead() CXX11_OVERRIDE
 500         {
 501                 unsigned char buffer[524];
 502                 irc::sockets::sockaddrs from;
 503                 socklen_t x = sizeof(from);
 504
 505                 int length = SocketEngine::RecvFrom(this, buffer, sizeof(buffer), 0, &from.sa, &x);
 506
 507                 if (length < Packet::HEADER_LENGTH)
 508                         return;
 509
 510                 if (myserver != from)
 511                 {
 512                         std::string server1 = from.str();
 513                         std::string server2 = myserver.str();
 514                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Got a result from the wrong server! Bad NAT or DNS forging attempt? '%s' != '%s'",
 515                                 server1.c_str(), server2.c_str());
 516                         return;
 517                 }
 518
 519                 Packet recv_packet;
 520
 521                 try
 522                 {
 523                         recv_packet.Fill(buffer, length);
 524                 }
 525                 catch (Exception& ex)
 526                 {
 527                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 528                         return;
 529                 }
 530
 531                 DNS::Request* request = this->requests[recv_packet.id];
 532                 if (request == NULL)
 533                 {
 534                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer for something we didn't request");
 535                         return;
 536                 }
 537
 538                 if (static_cast<Question&>(*request) != recv_packet.question)
 539                 {
 540                         // This can happen under high latency, drop it silently, do not fail the request
 541                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received an answer that isn't for a question we asked");
 542                         return;
 543                 }
 544
 545                 if (recv_packet.flags & QUERYFLAGS_OPCODE)
 546                 {
 547                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Received a nonstandard query");
 548                         ServerInstance->stats.DnsBad++;
 549                         recv_packet.error = ERROR_NONSTANDARD_QUERY;
 550                         request->OnError(&recv_packet);
 551                 }
 552                 else if (recv_packet.flags & QUERYFLAGS_RCODE)
 553                 {
 554                         Error error = ERROR_UNKNOWN;
 555
 556                         switch (recv_packet.flags & QUERYFLAGS_RCODE)
 557                         {
 558                                 case 1:
 559                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "format error");
 560                                         error = ERROR_FORMAT_ERROR;
 561                                         break;
 562                                 case 2:
 563                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "server error");
 564                                         error = ERROR_SERVER_FAILURE;
 565                                         break;
 566                                 case 3:
 567                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "domain not found");
 568                                         error = ERROR_DOMAIN_NOT_FOUND;
 569                                         break;
 570                                 case 4:
 571                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "not implemented");
 572                                         error = ERROR_NOT_IMPLEMENTED;
 573                                         break;
 574                                 case 5:
 575                                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "refused");
 576                                         error = ERROR_REFUSED;
 577                                         break;
 578                                 default:
 579                                         break;
 580                         }
 581
 582                         ServerInstance->stats.DnsBad++;
 583                         recv_packet.error = error;
 584                         request->OnError(&recv_packet);
 585                 }
 586                 else if (recv_packet.answers.empty())
 587                 {
 588                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "No resource records returned");
 589                         ServerInstance->stats.DnsBad++;
 590                         recv_packet.error = ERROR_NO_RECORDS;
 591                         request->OnError(&recv_packet);
 592                 }
 593                 else
 594                 {
 595                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Lookup complete for " + request->name);
 596                         ServerInstance->stats.DnsGood++;
 597                         request->OnLookupComplete(&recv_packet);
 598                         this->AddCache(recv_packet);
 599                 }
 600
 601                 ServerInstance->stats.Dns++;
 602
 603                 /* Request's destructor removes it from the request map */
 604                 delete request;
 605         }
 606
 607         bool Tick(time_t now)
 608         {
 609                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "cache: purging DNS cache");
 610
 611                 for (cache_map::iterator it = this->cache.begin(); it != this->cache.end(); )
 612                 {
 613                         const Query& query = it->second;
 614                         if (IsExpired(query, now))
 615                                 this->cache.erase(it++);
 616                         else
 617                                 ++it;
 618                 }
 619                 return true;
 620         }
 621
 622         void Rehash(const std::string& dnsserver)
 623         {
 624                 if (this->GetFd() > -1)
 625                 {
 626                         SocketEngine::Shutdown(this, 2);
 627                         SocketEngine::Close(this);
 628
 629                         /* Remove expired entries from the cache */
 630                         this->Tick(ServerInstance->Time());
 631                 }
 632
 633                 irc::sockets::aptosa(dnsserver, DNS::PORT, myserver);
 634
 635                 /* Initialize mastersocket */
 636                 int s = socket(myserver.sa.sa_family, SOCK_DGRAM, 0);
 637                 this->SetFd(s);
 638
 639                 /* Have we got a socket? */
 640                 if (this->GetFd() != -1)
 641                 {
 642                         SocketEngine::SetReuse(s);
 643                         SocketEngine::NonBlocking(s);
 644
 645                         irc::sockets::sockaddrs bindto;
 646                         memset(&bindto, 0, sizeof(bindto));
 647                         bindto.sa.sa_family = myserver.sa.sa_family;
 648
 649                         if (SocketEngine::Bind(this->GetFd(), bindto) < 0)
 650                         {
 651                                 /* Failed to bind */
 652                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error binding dns socket - hostnames will NOT resolve");
 653                                 SocketEngine::Close(this->GetFd());
 654                                 this->SetFd(-1);
 655                         }
 656                         else if (!SocketEngine::AddFd(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE))
 657                         {
 658                                 ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Internal error starting DNS - hostnames will NOT resolve.");
 659                                 SocketEngine::Close(this->GetFd());
 660                                 this->SetFd(-1);
 661                         }
 662                 }
 663                 else
 664                 {
 665                         ServerInstance->Logs->Log(MODNAME, LOG_SPARSE, "Error creating DNS socket - hostnames will NOT resolve");
 666                 }
 667         }
 668 };
 669
 670 class ModuleDNS : public Module
 671 {
 672         MyManager manager;
 673         std::string DNSServer;
 674
 675         void FindDNSServer()
 676         {
 677 #ifdef _WIN32
 678                 // attempt to look up their nameserver from the system
 679                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find a working server in the system settings...");
 680
 681                 PFIXED_INFO pFixedInfo;
 682                 DWORD dwBufferSize = sizeof(FIXED_INFO);
 683                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, sizeof(FIXED_INFO));
 684
 685                 if (pFixedInfo)
 686                 {
 687                         if (GetNetworkParams(pFixedInfo, &dwBufferSize) == ERROR_BUFFER_OVERFLOW)
 688                         {
 689                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 690                                 pFixedInfo = (PFIXED_INFO) HeapAlloc(GetProcessHeap(), 0, dwBufferSize);
 691                         }
 692
 693                         if (pFixedInfo)
 694                         {
 695                                 if (GetNetworkParams(pFixedInfo, &dwBufferSize) == NO_ERROR)
 696                                         DNSServer = pFixedInfo->DnsServerList.IpAddress.String;
 697
 698                                 HeapFree(GetProcessHeap(), 0, pFixedInfo);
 699                         }
 700
 701                         if (!DNSServer.empty())
 702                         {
 703                                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first active resolver in the system settings.", DNSServer.c_str());
 704                                 return;
 705                         }
 706                 }
 707
 708                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "No viable nameserver found! Defaulting to nameserver '127.0.0.1'!");
 709 #else
 710                 // attempt to look up their nameserver from /etc/resolv.conf
 711                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "WARNING: <dns:server> not defined, attempting to find working server in /etc/resolv.conf...");
 712
 713                 std::ifstream resolv("/etc/resolv.conf");
 714
 715                 while (resolv >> DNSServer)
 716                 {
 717                         if (DNSServer == "nameserver")
 718                         {
 719                                 resolv >> DNSServer;
 720                                 if (DNSServer.find_first_not_of("0123456789.") == std::string::npos)
 721                                 {
 722                                         ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "<dns:server> set to '%s' as first resolver in /etc/resolv.conf.",DNSServer.c_str());
 723                                         return;
 724                                 }
 725                         }
 726                 }
 727
 728                 ServerInstance->Logs->Log("CONFIG", LOG_DEFAULT, "/etc/resolv.conf contains no viable nameserver entries! Defaulting to nameserver '127.0.0.1'!");
 729 #endif
 730                 DNSServer = "127.0.0.1";
 731         }
 732
 733  public:
 734         ModuleDNS() : manager(this)
 735         {
 736         }
 737
 738         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 739         {
 740                 std::string oldserver = DNSServer;
 741                 DNSServer = ServerInstance->Config->ConfValue("dns")->getString("server");
 742                 if (DNSServer.empty())
 743                         FindDNSServer();
 744
 745                 if (oldserver != DNSServer)
 746                         this->manager.Rehash(DNSServer);
 747         }
 748
 749         void OnUnloadModule(Module* mod)
 750         {
 751                 for (unsigned int i = 0; i <= MAX_REQUEST_ID; ++i)
 752                 {
 753                         DNS::Request* req = this->manager.requests[i];
 754                         if (!req)
 755                                 continue;
 756
 757                         if (req->creator == mod)
 758                         {
 759                                 Query rr(*req);
 760                                 rr.error = ERROR_UNLOADED;
 761                                 req->OnError(&rr);
 762
 763                                 delete req;
 764                         }
 765                 }
 766         }
 767
 768         Version GetVersion()
 769         {
 770                 return Version("DNS support", VF_CORE|VF_VENDOR);
 771         }
 772 };
 773
 774 MODULE_INIT(ModuleDNS)
 775